1. Field of the Invention
The present invention generally relates to a strip test method, and more particularly to a strip test method, wherein the semiconductor devices which are failed in the first electrical test can be electrically tested again by the probe set in which the electrical test is successful in the first electrical test.
2. Description of the Related Art
U.S. Pat. No. 6,720,786, entitled “Lead Formation, Assembly Strip Test and Singulation System” discloses an integral system for testing semiconductor devices. Referring to FIG. 1, a functional test device includes a test module 20 and a base 24. The test module 20 has a plurality of probes 22. Generally, a plurality of molded semiconductor devices 12 are assembled (packaged) on matrix-type lead frame structures in which the semiconductor devices 12 are arranged in multiple rows and columns. Before being singulated (separated) into individual molded semiconductor devices 12, the molded semiconductor devices 12 are loaded to the base 24, and then are tested while the probes 22 simultaneously, respectively and electrically contact the leads 14 of the molded semiconductor devices 12 so as to process an electrical test, thereby reducing manufacturing time and costs. The term “assembly strip 10” is adapted to describe the integral structure formed by such a matrix-type lead frame structure with the molded semiconductor devices 12 packaged thereon. The term “strip test” is adapted to describe the electrical test before the molded semiconductor devices 12 are singulated.
In addition, referring to FIG. 2, it depicts a conventional strip test method. The strip test method includes the following steps. In step 48, an assembly strip 10 is inputted in a test area. In step 50, the assembly strip 10 is loaded to the base 24. In step 52, the probes 22 of the test module 20 simultaneously, respectively and electrically contact the leads 14 of the semiconductor devices 12 of the assembly strip 10, so as to process an electrical test. In step 54, the assembly strip 10 is unloaded from the base 24. In step 56, it is judged whether any semiconductor device 12 is failed in the electrical test or not. If the answer is “No”, the strip test method goes to step 58; and if the answer is “Yes”, the strip test method returns to step 50. In step 58, the assembly strip 10 is outputted from the test area.
However, according to the conventional strip test method, the assembly strip will be unloaded from the base after an electrical test of the assembly strip is finished. If some semiconductor devices are failed in the electrical test, the original assembly strip must be loaded to the base again and then another electrical test of the assembly strip is processed, such that the conventional strip test method will increase manufacturing time and decrease the production output. Furthermore, when another electrical test of the assembly strip is processed again, the semiconductor devices which are failed in the first electrical test will be still corresponding to the same probes in the first electrical test. If these probes malfunction, the test result of the second electrical test of the semiconductor devices which are failed in the first electrical test may be still wrong.
Accordingly, there exists a need for a strip test method and a functional test device capable of solving the above-mentioned problems.